its a bit badly drawn sorry i could have done it better by separating out the various bits i did it for fun its quite easy you have more or less lumps a stable vref original was a zener replace with a the v pot vr just feeds a darlington tranny via u feed back comes from a big npn emitter off board the rh opamp just measure the op current and turns stuff off with d basically a or gate a neg v for the opamps is a cockroftwalton thing zener lower left the most difficult bit drawingwise is the two power grounds joined with the current sense r q is a bit of protection against a missing negative rail q is a led driver for ilim did a pcb layout but never got it built